Vesicular prints and process of making same



United States PatentO VESICULAR PRINTS AND PROCESS OF MAKING SAME Clifford E. Herrick, Jr., Easton, Pa., and Ann K. Balk, (lwego, N. Y., assiguors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application December 12, 1951,

Serial No. 261,375

17 Claims. (Cl. 957) This invention relates to a method of preparing a photosensitive vesicular print material by forming a solution in a solvent of a thermoplastic, hydrophobic resin such as cellulose acetate with a resinous copolymer of a vinyl compound such as methyl vinyl ether and an ethenoid dicarboxylic acid compound such as maleic anhydride, coating this solution on to a support such as glass or black paper, drying to make a continuous film, treating the coating with a moist base such as ammonia vapor to make it hydrophilic, applying an aqueous solution of a stabilized photosensitive diazonium compound and drying. The invention also relates to the resulting substantially clear, photosensitive, vesicular print material, to the method of preparing stable vesicular prints therefrom by irradiating with actinic light through a design and then subjecting to elevated temperatures for short times to develop and stabilize the images, as well as to the resulting stable vesicular prints.

The art is familiar with photographic vesicular images prepared from a light sensitive layer made up from a hydrophilic material such as gelatin and a photosensitive diazo compound which liberates nitrogen gas upon photodecomposition. The image is developed by treatment with steam or water, whereby the hydrophilic layer softens and the nitrogen gas therein expands forming minute vesicles which refract light which strikes the layer. This causes an appearance of whiteness by reflected light and darkness by transmitted light. Sometimes the resulting print is given a treatment with a coupling compound to render the unexposed diazo material non-photosensitive, to prevent subsequent undesirable bubble formation in the unexposed or clear areas upon subsequent overall exposure to ordinary light and moisture.

Many disadvantages are inherent in this process and the resulting prints. The development operation is cumbersome and critical, and gives strong relief efiects which are undesirable in photographic prints. In the treatment of the undecomposed diazo material with a coupling component an azo dye is formed, and this prohibits the use of foil vesicular prints as photographic negatives; furthermore, the white areas are badly colored thereby.

A particularly disadvantageous feature thereof is the instability of the vesicular prints in the presence of moisture; since the hydrophilic medium absorbs moisture and softens, the minute vesicles collapse and the image is lost.

An improvement in this vesicular print process is the use of a single application of heat in the development st p, giving clean whites, and improved tone gradation through the use of a non-reflecting, opaque backing for ositive prints. However. even these improved prints leave much to be desired from the viewpoint of stability toward moisture.

H has been found, in accordance with the invention,

that the above discussed drawbacks may be overcome.

and superior vesicular print materials may be prepared by forming a solvent solution of 5 to 1 parts by weight of a thermoplastic, hydrophobic resin and 1 to 6 parts or" a compatible resinous copolymer of about one moi of a vinyl compound with about one mol of an ethenoid dicarboxylic acid compound, coating it on a support and drying to form a continuous layer, treatin the layer w th a moist base to make it hydrophilic, then sensinzmg this layer by application of an aqueous solution of a stabilized photosensitive diazonium compound, preferably including an acidic diazo stabilizer and a plasticizer, and drying. Upon irradiating the resulting material with actinic light through a design, and then subjecting it to an elevated temperature for a short time, the image is developed and the water sensitivity of the layer is greatly reduced. If desired, the resulting vesicular print may be re-exposed to the actinic or ultraviolet light at ambient temperatures to destroy remaining diazo compound.

The resulting vesicular prints are stable at ambient temperatures even in the presence of moisture, exhibiting perfectly clean whites with no discoloration in exposed or unexposed areas. They show no grain and have very soft toe gradation with details in both highlight and shadow areas.

The objects achieved in accordance with the invention as described herein include the provision of vesicular images with excellent tone gradation and clean whites; the provision of vesicular prints which show good stability to actinic light, moisture and water at ambient temperatures; the provision of processes for making either positive or negative vesicular prints having the above-mentioned characteristics; the provision of a photosensitive vesicular print layer which is hydrophilic and gas impermeable during the irradiation but which becomes much more hydrophobic during the elevated temperature development treatment; the provision of methods for preparing photosensitive vesicular print materials by forming solvent solutions of thermoplastic hydrophobic resins and compatible resinous copolymers of a vinyl compound with an ethenoid dicarboxylic acid compound, coating this on a support, drying, treating with a moist base, applying an aqueous solution of a stabilized photosensitive diazonium compound and drying; and other objects which will become apparent as details or embodiments of the invention are set forth hereinafter.

In order to facilitate a clear understanding of the invention, the following preferred specific embodiments are described in detail:

Example 1 A coating formulation was prepared from the following:

12 parts vinyl methyl ether and maleic anhydride copolymer (parts are by weight) 6 parts cellulose acetate 19 parts ethylene glycol mono methyl other 112 parts acetone 2 parts polyvinyl methyl ether (plasticizer) The solids were Well dispersed in the liquids and the entire mixture was rolled for several hours to dissolve. The solution was coated on black paper at 25 mils wet film thickness with a Bird type or other applicator, and dried. The layer was passed through ammonia vapors several times (for a total contact time of minute at F.). then washed with dilute HCl (e. 2.. 2 cc. 37% HQ! added to 100 cc. of water). dried at 50 C., and sensitized by immersion in the following solution:

10 parts N,N-diethylaniline, 4-diazonium chloride, zinc chloride double salt 10 parts citric acid 8 parts ethanol 17 parts ethylene glycol. Entire solution is diluted to about 100 parts with water.

The dried layer was exposed to ultraviolet rays through a suitable positive transparency for 30 seconds to about 3 minutes, depending upon the strength of the light source, and developed by the sudden application of heat, as in a rotary ironing mangle (at a temperature of about F. and a contact time of about 5-6 seconds); and a stable image was formed, possessing excellent whites, soft gradation, and good resistance to moisture at ambient temperatures. A brief re-exposure to direct actinic li ht at ambient temperatures destroys the remaining diazo compound without adversely aifecting the prints.

Example 2 In this example the procedure was as in Example 1, except that the following coating formulation was used:

12.66 parts vinyl methyl ether, maleic anhydride copolymer,

' a sess:

6:33 parts cellulose acetate 19.0 parts ethylene glycol mono methyl ether 112.0 parts acetone 1.0 part polyvinyl methyl ether The-product gaye prints comparable to those in Example 15', by the above-described method.

.Exampl .3

In example the procedure was as in Example 1, except that the following coating formulation was used: 3.0 parts vinyl methyl ether, maleic anhydride copolymer :6 5 par s c l ulose acetate I s-ethy e e. yco mor m t y ether pa s c t n @150 part PQlYY-ifly met yl, et "The product gave prints similar to those in Example 1,

by the above-described method.

Example 4 '-terials gave prints of good quality and resistance to moisture at ambient temperatures.

' Example 5 In this example the procedure was as in Example 1, except that the coating was at 18 mils thlekness, and. the following coating formulation was used:

1.5 parts 2-methoxy-ethyl vinyl ether, maleic anhydride copolymer 3.5 parts polyvinyl acetate 2.8 Pa t ceton 51mins et y e e yc m o m thy e h r Example 6 The procedure used in this example was the same as in Example 5, except that the following coating formula- 1.5 parts vinyl isobutyl ether, maleic anhydride copolymer 3.5, parts nitro cellulose 28,. parts acetone 5..pa.rts ethylene glycol mono. methyl ether 'Following the procedure in Example 1, the resulting materials gave prints, and these showed resistance to moiswture at ambient temperatures.

Example 7 T e p e ur u in is ex mpl s the sameas in vExample excep hat. th t low ue oat n formulation is used:

3.0 parts vinyl methyl ether, maleic anhydride copolymer 7.0 parts methyl methacrylate, polymerized S 0' parts acetone 2:. parts. ethylene .glycq I Q JQ m thyl Qther The vesicular print material is processed as in Example 1.

Example 8 The procedure'used in this example'was the same as in Example 5, except that the following coating formulation was used: 1.5 parts vinyl isobutyl ether, maleic anhydride copolymer 3.5 parts polyvinyl acetate 31.0 parts hutyl acetate 5.0 parts ethylene glycol mono methyl ether The vesicular print material was processed as in Exampl Example 9 The procedure used in this example was the same as in Example, 5, except that the following coating formula-.

tion was used:

3.33 parts Z-methoxy ethyl vinyl ether, maleic anhydride copolymer 6.66 parts cellulose acetate '57; parts acetone 95. parts ethylene glycol mono methyl ether Following-the procedure in Example 1, the resulting materials gave prints of superior resistance to moisture at ambient temperatures.

Example. 10

Theproccdure used in this example was the same as in Example 5 except that the following coating formulation was used:

333' :parts Z-ethoxy ethyl vinyl ether, maleic anhydride copolymer 6.66 parts cellulose acetate 57 parts acetone 9.5 parts ethylene glycol mono methyl ether used. Insteadxof treating with ammonia vapors, moist vapors of another volatile base such as organic amines and the like may be used; or alternatively, an aqueous solution of a basic material may be used to render the layerhydrophilic. The thermoplastic hydrophobic resin may be any such resin or mixture of resins which is compatible with :the copolymer material providing it remains essentially hydrophobic under the treatment by which the copolymer material is rendered hydrophilic. Copolymers of vinyl compounds with ethenoid dicarboxylic acid compounds are known. In general they are thermoplastic-solids and are made up from a ratio of about one-mol of the vinyl compound with about one mol of the ethenoid dicarboxylic acid compound; the latter may be maleic anhydride or a substituted maleic anhydride suchas one containing a lower alkyl group or the like. Mixtures of resins may be used, as may mixtures .of the ethenoid compounds.

The proportions of resin and copolymer should be such as to give compatible compositions when dried, i. e., give .a substantially clear layer or film.

Desirable light sensitive diazonium compounds are stabilizedas .diazo oxide or as the z1nc chloride, or the like, metallic double salt and are derived from aromatic para- .diamines,.p,articular1y N-mono or (ii-substituted benzene para=diamincs Or from para-ammo diphenyl amine; and

.out by direct contact with a heated surface. However,

other heating means, such as radiant heat may be used.

For some applications, where water resistance is'not critical, direct steam may be used.

It is indeed surprising that the processes of the invention maybe cmied out in a most practical manner, and

yet give vesicular prints which combine good photographic quality with a high degree of stability.

Variations and modifications of the invention will be apparent to one skilled in the art in view of the foregoing disclosures, and it is intended to include Within the invention all such modifications and variations except as do not come within the scope of the appended claims.

We claim:

1. A method of preparing a photosensitive vesicular print material which comprises forming a compatible solvent solution of an amount in the range of 5 to 1 parts by weight of a thermoplastic, hydrophobic resin selected from the group consisting of cellulose acetate, nitrocellulose, polyvinyl acetate and polymethyl methacrylate, and an amount in the range of 1 to 6 parts of a resinous copolymer of about one mol of a vinyl ether with about one mol of a maleic acid compound, said hydrophobic resin and said copolymer being compatible, said amounts being selected to give a substantially clear layer upon drying, coating it on a support and drying to form a substantially clear layer, treating said layer with a moist water soluble nitrogenous base to make it hydrophilic, photosensitizing this layer by application of an aqueous solution of a stabilized photosensitive diazonium compound, and drying.

2. The method of claim 1 wherein the maleic acid compound is maleic anhydride.

3. The method of claim 1 wherein the resin is cellulose acetate and the copolymer is of a vinyl ether and maleic anhydride.

4. The method of claim 3 wherein the diazonium compound is N,N-diethylaniline-4-diazonium chloride, zinc chloride double salt.

5.1 The method of claim 4 wherein the ether is methyl VlIlY 6. The method of claim 4 wherein the ether is 2-methoxyethyl vinyl.

7. The method of claim 4 wherein the ether is Z-ethoxyethyl vinyl.

8. The method of claim 1 wherein the resin is polyvinyl acetate and the copolymer is of a vinyl ether and maleic anhydride.

9. The method of claim 8 wherein the diazonium compound is N,N-diethylaniline-4diazonium chloride, zinc chloride double salt.

10. The method of claim 9 wherein the vinyl.

11. The method of claim 9 wherein the ether is 2- rnethoxyethyl vinyl.

12. The method of preparing a stable vesicular print which comprises irradiating with actinic light through a design, a photosensitive print prepared according to the method of claim 1 to form a latent image, and then heating said material to develop and stabilize the image.

13. A photosensitive vesicular print material prepared according to the method of claim 1.

14. A photosensitive vesicular print material prepared according to the method of claim 2.

15. A photosensitive vesicular print material prepared according to the method of claim 3.

16. A photosensitive vesicular print material prepared ether is isobutyl according to the method of claim 4.

17. A photosensitive vesicular print material prepared according to the method of claim 5.

References Cited in the file of this patent UNITED STATES PATENTS 2,156,069 Schlack Apr. 25, 1939 2,239,704 De Boer Apr. 29, 1941 2,397,866 McQueen Apr. 2, 1946 FOREIGN PATENTS 318,511 Great Britain Aug. 7, 1930 402,737 Great Britain Mar. 5, 1932 524,786 Great Britain Aug. 14, 1940 563,804 Great Britain Aug. 30, 1944 

1. A METHOD OF PREPARING A PHOTOSENSITIVE VESICULAR PRINT MATERIAL WHICH COMPRISES FORMING A COMPATIBLE SOLVENT SOLUTION OF AN AMOUNT IN THE RANGE OF 5 TO 1 PARTS BY WEIGHT OF A THERMOPLASTIC, HYDROPHOBIC RESIN SELECTED FROM THE GROUP CONSISTING OF CELLULOSE ACETATE, NITROCELLULOSE, POLYVINYL ACETATE AND POLYMETHYTL METHACRYLATE, AND AN AMOUNT IN THE RANGE OF 1 TO 6 PARTS OF A RESINOUS COPOLYMER OF ABOUT ONE MOL OF A VINYL ETHER WITH ABOUT ONE MOL OF A MALEIC ACID COMPOUND, SAID HYDROPHOBIC RESIN AND SAID COPOLYMER BEING COMPATIBLE, SAID AMOUNTS BEIN SELECTED TO GIVE A SUBSTANTIALLY CLEAR LAYER UPON DRYING, COATING IT ON A SUPPORT AND DRYING TO FORM A SUBSTANTIALLY CLEAR LAYER, TREATING SAID LAYER WITH A MOIST WATER SOLUBLE NITROGENOUS BASE TO MAKE IT HYDROPHILIC, PHOTOSENSITIZING THIS LAYER BY APPLICATION OF AN AQUEOUS SOLUTION OF A STABILIZED PHOTOSENSITIVE DIAZONIUM COMPOUND, AND DRYING. 